Rheostat-switch.



No. 650,582. Patented May 29, I900.

' B. FULLER. Y

BHEOSTAT SWITCH.

(Application filed Oct. 27, 1899.)

(No Model.)

o 0 o ofo 10 0 o o 0 o o A o o 0 o o o if? {L 52/6/2421"; 2/2. if; fivei vfizw 7 8h auw u I! g UNITED STATES PATENT OFFICE.

RODOLPHUS FULLER, OF DETROIT, MICHIGAN.

aneosrAr-swiroa.

SPECIFICATION forming part of Letters Patent NO. 650,582, dated May 29, 1900.

Application filed October 27, 1899- To aZZ whom, it may concern:

Be it known that I, RODOLPHUS FULLER, a citizen of the United States of America, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Rheostat- Switches, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to that kind of rheostat-switch in which a pivoted contact-arm cooperates with a series of fixed contacts to cut the resistance out or introduce it into the motor-circuit by moving the contact-arm over the fixed contacts in starting and stopping the motor.

My invention consists in the peculiar construction and arrangement of parts whereby the switch operates automatically as a safety and limit sWitch,whe-reby the contact-arm returns automatically to its starting position and opens the circuit of the motor upon a failure of the current or if the same should ex ceed a predetermined maximum, all as more fully hereinafter described, and shown in the accompanying drawings, in which- Figure l is a face view of my rheostat switch, showing it as it appears fastened in position to a vertical wall. Fig. 2 is a plan as it appears looking at it from the under side. Fig. 3 is a section on line 00 00, Fig. 1. Fig. 4 is a face view similar to Fig. 1 and showing in diagram the electrical circuits.

A is a box in which the resistance-coils are inclosed. B is the cover of the box, made of slat or other insulating material. ()is the piv oted contact-arm. D represents the fixed contacts to which the terminals of the resistancecoils are connected. D is the dead-contact at the starting-point. E and F are stops limiting the movement of the contact-lever. G is the pivot of the contact-lever. H is a spring inclosed in the hub c of the contact-lever and operating by its tension to move the contactlever into the starting position when released. I is a contact-spring secured to the contactlever, and J J are binding-posts, all the aforementioned parts being of known construction and operation.

My invention consists in the combination, with the above parts, of a combined retaining and releasing magnet K, which is connected Serial No. 734,935. (No model.)

into the motor-circuit and has two pole-pieces a a, connected to opposite ends of the core, and two independent armatures L and M, adapted to contact therewith.

The armature L is for retaining the contactarm in any position to which it may be adjusted. It is provided with a split hub b, sleeved upon the hub c of the contact arm, and a clamping-screw d passes through the split ends for the purpose of clamping the armature upon the hub of the contact-arm to operate in the manner more fully hereinafter described.

The armature M is pivoted on the under side of the pole-pieces of the magnet, so that gravity will tend to hold it out of contact therewith. Its free end projects through a slotted guide 6, which carries an adjustingscrew f, by means of which its proximity to the opposite pole of the magnet may be adjusted, a suitable index being preferably engraved on the guide.

To the free end of the armature M is socured a contact-spring g, which is adapted to press against two fixed contacts 72 h when the armature is closed upon the poles of the magnet, and these two fixed contacts are open terminals of a short circuit around the magnet.

For a better understanding of the operation of my device I show in Fig. 4. the electrical connections, in which N represents the source of electricity, and O the motor controlled by the device. From the generator the current passes through conductor 1, binding-post J, conductor 2, contact h, conductor 3, coil of magnet K, conductor 4, contact h, conductor 5, pivot G, flange p of pivot, contact-spring I, the contact D upon which the contact-arm rests, conductor 6, binding-post J, conductor 7, field-coils and armature-coils of motor, and conductor 8 to source of electricity, thus completing the circuit in the position of the parts shown in Fig. 4., which is the position when the motor is in normal operation. When the motor is at rest, the contact-arm is on the dead contact D, as in Fig. 1, the circuit of the motor is open, and the magnet K is not energized. In starting the motor the contact-arm is'gradually moved over the contacts D, which closes the motorcircuit first through the whole resistance and thence cutting the same out step by step in the usual manner. The

armature L, being frictionally clamped upon the hub of the contact-arm, moves with the contact-arm until it rests against the poles of provided the armature is brought into contact with the poles of the magnet, which may be done by the hand of the operator inde pendently of any movement of the contactarm. Upon a failure of current from any cause whatever the magnet K would cease to hold the armature and allow the spring II to automatically retract the contact-arm to its starting position. The same would occur if the current exceeds a certain maximum, which increases the magnetic strength of the magnet to cause it to attract the armature M and close the circuit around the magnet through the fixed contacts h h, thereby deenergizing the magnet and causing the oontact-arm to t] y back into its starting position again.

The set-screw f serves. to regulate the amount of air-gap between the poles at and the armature M, as required to operate at a current of any given maximum strength, as shown 011 the index.

To prevent the armature L from sticking to the poles of the magnet, I preferably insert a small copper pin 70 into the outerpole, which projects just a trifle beyond the pole to keep the armature out of direct contact.

I am aware that rheostat-switches have been devised heretofore which are intended to accomplish the same results; but they are more complicated and embody usually two or more magnets, while I have but one magnet with a single coil operating both as a retaining and as a releasing magnet. Further, I dispense with intervening mechanism between the armatures and the contact-arm, (the armature L being virtually a part of the contact-arm,-) and as a result of my construction return it to its starting position and open the circuit when released, of an electromagnet in the circuit of said motor, a retaining-arm pivotally mounted upon the contact-arm and adapted to constitute an armature and be held in position by said electromagnet independent of the position or movement of the contact-arm, anda friction device interposed between saidretaining-arm and the contactarm.

2. In a rheostat-switch for electric motor, the pivoted contact'arm thereof having a hub, a retracting-spring inclosed within said hub and a retaining-arm pivotally clamped upon said hub and having a frictional resistance thereon exceeding the powerof the retractingspring and adapted to permit a relative movement between said contact-arm and the retaining-arm in operating the switch.

3. In a rheostat-switch for electric motor, the combination with a series of fixed contacts and a pivoted contact-arm having a retracting-spring to automatically open the circuit when released, a retaining -arm pivotally clamped upon the hub of the contact-arm independently movable thereon and adapted to hold thesame in position independently movable of said retaining-arm, and an ele'ctro magnet in the circuit of the motor having pole-pieces, adapted to be magnetically connected by said retaining-arm and hold the same in position when the electromagnet is energized.

4. In a rheostat-switch for electric motor, the combination with the pivoted contact-arm adapted to close the circuit of the motor and having a retracting device to automatically return it to its starting position and open the circuit of the motor when released, a retaining-arm pivotally clamped upon a hub on the contact-arm and adapted to hold the same in position independently movable thereof, an electromagnet in the circuit of the motor hav ing pole-pieces adapted to be magnetically connected by said retaining-arm to hold the same in position, and an armature adapted to cooperate with said electromagnet independent of the retaining-arm and adapted to short-circuit the same, at the maximum current strength the motor is designed to carry.

In testimony whereof I affix my signature in presence of two witnesses.

nonotrnus FULLER.

Witnesses:

Or'ro F. BARTHEL, V. D. KINNER. 

